Handling of duplicate tags on document

[nleanba]

It's currently possible to add an parameterisable tag multiple times to a document, as long as the values are different (otherwise it "fails" silently).

It is however not possible to delete specific instances of those off a document, as one can only remove all tags wit a specif label from a document.

It should either be made possible to remove only selected tag/value instances or the practice of duplicate tagging made impossible.

[nleanba]

See commit 72a5686 of tridoc/tridoc-cockpit